1. Field of the Invention
The present invention relates to a photodetector, a display device including the photodetector, and an electronic device including the photodetector.
2. Description of the Related Art
In resent years, a touch panel in which a device including a circuit that detects light (also referred to as a “photodetector”) and a pixel circuit of a display device are formed in an integrated manner has attracted attention. For example, Patent Document 1 discloses a liquid crystal display device in which an optical sensor element that detects the intensity of visible light (hereinafter referred to as a visible light sensor) and an optical sensor element that detects the intensity of infrared light (hereinafter referred to as an infrared light sensor) are disposed in a display panel.
In the structure of Patent Document 1, a touch panel function with high accuracy is realized by disposing the visible light sensor and the infrared light sensor. With the structure, even when the detection accuracy of the visible light sensor is decreased by noise due to light such as outside light depending on the environment under which the liquid crystal display device is placed, infrared light that is not influenced by visible light is detected by the infrared light sensor with photosensitivity different from that of the visible light sensor; thus, accurate positional detection is achieved under a wide range of environmental illuminance.